Some links to various tandem or cycling related sites:
The South East London region No longer organises rides, their area has been included in the Surrey and Sussex group, and the Kent group. The link takes you to the archive of their website.
The Tandem Club UK has an extensive website with lots of information, chat room and for sale area, and most importantly news and details of the forthcoming National and International events.
We often organise joint rides with the Kent group, and our Christmas Ride and lunch is a joint effort (well to be fair normally Cliff and Pauline!).
The Cyclists' Touring Club, now known at Cycling UK but usually referred to as the CTC also a very useful site with lots of information.